Money is useful to people because it is one of the options below as your
a. a medium of exchange
b. prestigious
c. nice to look at
d. something that makes you feel good

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =

the awnser is d you right bro